The present application relates generally to ice making machines, and specifically to controls and sensors as used therein.
Ice making machines are well known in the art, and typically include an ice cube making mechanism located within a housing along with an insulated ice retaining bin for holding a volume of ice cubes produced by the ice forming mechanism. In one type of ice maker a vertically oriented evaporator plate is used to form a slab of ice characterized by a plurality of individual cubes connected by ice bridges there between. As the slab falls from the evaporator plate into the ice bin, the ice bridges have a tendency to break forming smaller slab pieces and individual cubes. As is well understood, the ice slab is formed by the circulating of water over the cooled surface of the evaporator plate, the plate forming a part of a refrigeration system including a compressor and a condenser. Water that is not initially frozen to the evaporator falls into a drip pan positioned below the evaporator and is pumped there from back over the evaporator. After sufficient time has elapsed, ice of a desired thickness will form on the evaporator.
Of critical importance to ice makers of this general type, is knowing when the ice is of the desired thickness to be harvested. Once the harvest point is reached, the making of ice is discontinued by stopping the flow of water over the evaporator and the cooling thereof. The evaporator plate is then heated, typically by the use of hot gas from the refrigeration system. The ice slab then melts slightly releasing its adhesion to the plate so that it can fall into the bin positioned there below. Various controls have been proposed and used over the years to signal the harvest point.
Occasionally, however, the proper functioning of such harvest controls can be interfered with by the imperfect formation of ice on the evaporator. For example, it is known that under certain high ambient conditions, for example, ice can initially form on the evaporator that is not well adhered thereto. Such ice can prematurely fall from the evaporator prior to reaching the desired harvest point. This ice can be in the form of pieces of hard ice or can even comprise a slush. This xe2x80x9cvolunteer harvestxe2x80x9d ice can fall into the drip pan and cause disruption of the recycling flow of the water by interfering with the operation of the pump that provides therefor, and can also block or otherwise compromise the operation of the ice harvest detection equipment. In either case, proper operation of the ice maker can be interfered with resulting in premature ice harvest, lack of harvest, damage to the ice maker and the like. Accordingly, it would be desirable to have an ice maker that prevents improper ice formation that results in premature falling thereof from the evaporator.
The ice maker herein works in the conventional manner wherein a refrigeration system provides for cooling of the evaporator. Water is first circulated over the evaporator as the evaporator is cooled. A temperature sensor is located in the water recirculating system and a microprocessor monitors the temperture of the circulating water. Once a predetermined temperature is reached, for example 40 degrees Fahrenheit, water circulation is stopped. However, the compressor continues to run and cool the evaporator for a predetermined period of time, such as, one minute. The pump is then turned on and water again circulated over the evaporator initiating the ice making cycle.
Those of skill will appreciate that the first cycling of the water permits the cooling thereof to a relatively cold temperature, but above freezing so that ice is not formed on the evaporator. After the first water circulating is stopped the evaporator is permitted to cool down to a temperature at which it is ready to form ice. Therefore, the control of the present invention insures that the water and the evaporator are both at sufficiently low temperatures such that initiation of ice formation will result in strong adherence of ice to the evaporator. As a result thereof, xe2x80x9cslushingxe2x80x9d or the formation of otherwise poorly adhered ice, is prevented.